We have established a collaboration with the Harvard School of Dental Science to assist in the analysis of a case-control study of Osteosarcoma that they initiated under a grant from NIEHS. One hundred and eighty-nine cases of osteosarcoma, 108 cases of other bone tumors and 163 controls from the same orthopedic service as the cases were interviewed, and a variety of biologic specimens were obtained. We will be collaborating on analyses of questionnaire data in an attempt to identify risk factors for the development of osteosarcoma. In addition, we will be taking the lead in assaying for levels of fluoride in unaffected bone and toe nails from a sample of cases and controls and in the analysis of these results. We will also be pursuing genetic and other risk factors for this cancer and its natural history.